#include <iostream>
#include <map>
using namespace std;

int main() {
    map<string, int> scores;

    scores["Tom"] = 75;
    scores["Alice"] = 88;
    scores["Bob"] = 92;

    for (auto it = scores.begin(); it != scores.end(); ++it) {
        cout << it->first << ": " << it->second << endl;
    }


    if (scores.count("Alice")) {
        cout << "Alice 的成绩是：" << scores["Alice"] << endl;
    }

    scores.erase("Tom");

    cout << "删除 Tom 后还有 " << scores.size() << " 个学生。" << endl;

    return 0;
}
